Method of making 2-sulfoethyl esters of fatty acids



United rates Fatent 2,821,535" METHOD OF MAKINGZZ-SULFOETHYLESTERSB F. ACIDS Eugarc; Bi'iftonandfAi-thurlR sex on; MidlimdQlVIichi, a$signors'tot =Tl1e Dow Chemical Company," Midland,

Miehi; a'corporation of Delaware NorDrawin'gr Application-Eebruary 29, 1956r Serial No. 568,427.

Thisr-inventionvconcernsca niethodTof-::making:.2-sulforethyhesters'fofiefatty acidss- It relatesimorerparticnlarlwto an improved-.ip'rocedure';ferr-makingrZPsuIfoethyliesters ofi fatty acids:

U. S. PatentsNow1;8.81;172makes the sodium salt ofoleic acid ester of hydroxyethanesulfonic acid (isethionic acid) by reacting sodium'hydfoxyethane sulfonate and oleic acid chlorideat temperatures-between 30 and-100 C. The resultingproduct is kneadedr with anh'ydrousrsodie um carbonatetofneutralize the same; after T which the product in pure state is recovered by crystallizationfrom alcohol? The prior method leaves much -to be: desired, Particu larlyrwith regard to manufacture "of-.thevestei' 'on' a'com, mercialsealer One dis advantage is: thedifiieultyfof? 011-" taining complete reaction 'of the ingredientsr- This result-s in alowyieldofithedesired=ester productz The neutralized mass is unstable and requires further stepsto -obt-ain;a pure product. Other drawbacks include the di-flicu-lties'mf further a processing; steps which; involve .handling. and ,the recover-y," of solvents Hi0 obtaina; stable product liavingaza: desired purity.-

Itis-an object of the invention to;provide-an-mprovedi process for making 2-sulfoethyl esters I of fatty acids from salts of hydroxyethane= sulfonic acid, ;i.- e. isethionates; and .fattyiacid-chlorides, which-process results inisubstan tiallycomplete conversion ofthe starting. materials into the desiredffattyacid" ester'product; Another object-is to provide aaprocess for reacting ;.a--salto-isethionie aeid and-afatty acid? chloride *toyield 'a-corresponding-2-sulfoethyl -fattyyacid= ester' product which is suitable for use- 2,821,535 Patented Jam 28;1958.

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or carbo'ri dioxide," ttrrc'mgli thereaction v zone, at atmosplieric p're'ssureoi thereabout, or subatmospheric pressure, to displace the by-product hydrogenchloride from the reaction, the ingredients are.caused to react readily, rapidly and substantially completely with one another to form the corresponding ester in good yield,',andupon neutralizing Abe-reacted. materialvw-i-th an-- alkalic'results in a free; fiowing powder on grannlan'produ'ct which is stable' 'and isr-suitable for? use; as: a? surfactant without furtheri puris ficationt or treatment.

Saltsof isethionic acid -to be employed asrstarting materials are? the alkali and alkalineearthm'etah salts.- of isethionic acid such as ammonium isethionate, sodium isethionate, potassiumfisethionate; lithium isethionate, calcium isethionate, magnesium isethionate or barium isethionat; The -alkali metal"salts r of isethionic acid'are. referred." 7

Fatty-acid 'chloridestobe employed in the process, are. the acyl chlorides of fatty acids containingirom 12-to -18 carbon. atoms in'l'tlie molecul'ewsuch as fatty, acids derived. fi 'om'coconutfoil" (principally lauric acid), ,oleic acid 01- stea'riciacidf xample; of suitable acyl chlorides. are. lauroylichlorid, oleoyl"chloride or stearoyl chloride.

The "starting. materials are usually employed. in .stoich-i ornetric proportions, but can be employed in amounts.

- correspondingjto from 1 to'1.1,-.preferablyw from 1' to as; a wetting, dispersing or surface activeagent without,

furthenpurification; Still another object is to -pro.vide-improvementsin-a process for making-Z-sulfoethyl estersofi fatty acids-fromdsethionates and-fatty-acid chlorides; Other and related objectszmay appearsfrom theifollowingr description-\of-the invention.

According .tothe invention, the new; and improved. process comprises reacting .underanhydrousor-substantially. anhydrous conditions, a mixture of asalt of ise thionic acid and'a fatty acid chloride, i. e.- anacyl chlorideoiia fatty acid, containing .from-12-to18 carbon atoms in the molecule at temperatures-not. exceeding-170? (3,, preferably,=at temperatures between 90 and 115 C. until the exothermic reaction subsides, then attemperatures between 135 and- 1.70 C. while mechanically working the ingredients in admixture with o ne another and with? drawingthe vapors of the by-product hydrogemchloride from the reaction and thereafter neutralizingthe reacted. material with an alkali.

By carrying. outthereaction under anhydrous on sub? stantially; anhydrousconditions at temperatures between. 135 and .170 0., preferably from 140'to,160-C.,,whi-le: mechanically. Working. theingredients in intimate ad mixturewith one anotherand withdrawing gthe-vaplors of hydrogen chloride from-the=reactiong suitably bycarry ing-sloutthe.:reaction.-undensubatmospheric.pressure-onbyf;

passing a stream of an inert gas, e. g. nitrogen, helium 1.04, gram molecular proportions-of the salt of isethionic. a'cidper ram molecularvpr'oportion of the fatty acid "chloride employed.

The'react'ioirc'an'be carried out batchwise or in a con tinuous'rnannert A In practice; tlie"sal't"of"isethionic acid and. the fatty. acid"chloride startingimaterials are. mixed togetlierin, the desired roportions; suitab1y;at"roomf temperature ortliereabbut; and intimately incorporated with'oneane otlier, e. gib'y blendin'g in'amixeri Thereafter," the mix: ture 'is heatedtoabout C. toinitiatthe reaction,- which is exothermic. The miXtur'eIiSmaintained at "reac-' tion temperamres;xtietween andl70 C'., preferably. und'r subatmo'spheric. pressures while withdrawing vapors oif tlre-"b'yreduethydrogen. chloride rrom'the reaction: The, H drogen chloride .isfusu'all'yv withdrawn from" the reacti' on'at abouttlie'rateit'isforrriedf. As the reaction proceeds the" physical" condition" of the reaction mass changes from a non-viscous. li quidor slurryto' a'viscous. paste" and. then to a brittle mass which" granulates or crumblesreadilyiwhen cool and forms a. powderio'r fine particles. The productcan be further pulverizedor ground to a" uniform size; The product is mixedlwith a-powdere'd alkali such-gas sodium hydroxid;. potassium hydroxide; sodium'icarbonate'ior,potassiumwarbonate in amount 'sufli? ci'ent'to forma final product such'that'a 10 weight'perc'ent solution of the material in water has a pH value between 7 and 8.

The-process can. be carriedoutin continuous manner by mixing; the.-starting-,materials, eg,, acyl chloride. of fatty, acids; derived frloinrcoconut oil, (principally lauroyl. chloride) and sodium. isethionate,. at. room temperature.

or thereabout intliedesired. proportions to. obtain. a note viscous slurry, offthe, ingredients, feeding. the. slurryrintoa reactiomzonebwh'ereinitis. heated at reaction tempera: tures andmech'anicallyworkedby, a shearing, cutting.,and= blending;actionv which: forwardsthe mass through said reaction, zone, andiatithe. same time the vapors. of;by.- product hydrogen chloride are withdrawn, after which'the reactedjmass'. or. product, is. cooled and neutralizedv witli an a1kali',.e..g. sodiumrhydroxide, in powdered;form,.ancl is brokenror crushedto a granular or powdered. form.

The invention provides a novel process for readily, rapidly. and efiectively. reactingsalts of isethionic acid with v fatty acid;- chlorides. to. yield? the. corresponding isethionate ester. The neutralized ester products prepared subject to appreciable change in pH value upon storage, and are useful as wetting agents, dispersing agents, or emulsifying agents.

, The following examples illustrate ways in which the principle of the invention has been applied, but are not to be construed as limiting its scope.

Example I A charge of 228.5 pounds, approximately one pound mole of a mixture of fatty acid chlorides of which lauroyl chloride is the major constituent, containing not more than 30 percent by weight of the adjacent fatty acid chlorides and derived from fatty acids of coconut oil, and 148 pounds, one pound mole, of sodium isethionate (hydroxyethane sulfonic acid sodium salt of the formula HOCH CH SO Na) were placed in a mixer having blades adapted to knead and mechanically work the ingredients into a uniform mixture. The mixture was kneaded at room temperature for a few minutes, then was heated to a temperature of 90 C. to initiate the reaction. The temperature of the mixture was allowed to rise spontaneously to 135 to 150 C. under absolute pressures of from to 100 millimeters while withdrawing vapors of hydrogen chloride from the reaction zone, over a period of approximately 45 minutes. The mixture was then cooled while mixing at a temperature between and C. and was discharged from the reaction vessel. The product was obtained as white crumbly flakes. It was analyzed and found to consist of 94.6 percent by weigh-t of the sodium salt of isethionate ester of the fatty acids starting material. It was ground to powdered form and was mixed with powdered sodium hydroxide in amount sufiicient to form a substantially neutral final product. An aqueous 10 weight percent solution of the final product in water had a pH value of 7.5 at 25 C. After storage of the dry final product for a period of days at ordinary temperature, an aqueous 10 weight percent solution of the product had a pH value of 7.4.

For purpose of comparison, a similar experiment was carried out by heating the reactants with mixing at temperatures between 105 and 110 C. and evacuating the by-product hydrogen chloride over a period of 75 minutes. The product consisted of only 85 percent by weight of the sodium salt of isethionate ester of the fatty acids starting material. It was ground to a powdered form and was neutralized with finely divided sodium hydroxide. An aqueous 10 weight percent solution of the neutralized product had a pH value of 7.7. After storage of the dry neutralized product for 9 days at ordinary temperatures and pressures, an aqueous 10 weight percent solution of the material had a pH value of only 7.3. After 15 days it was 7.2, and after 27 days the pH value was 7.0.

Example 2 A charge of 776.5 grams (2.58 moles) of oleic acid chloride and 455 grams (28 moles) of sodium isethionate were mixed in a laboratory blender and heated at temperatures between 110 and 115 C. for a period of 1.25 hours while withdrawing vapors of by-product hydrogen chloride from the reaction and maintaining the mixture under absolute pressures between 10 and 50 millimeters. Thereafter, the mixture was heated at temperatures between 140 and 150 C. with mixing and withdrawing of HCl under reduced pressure for a period of 30 minutes, then was cooled to room temperature. Upon cooling, with agitation, the mixture was obtained as a granular waxy solid. It was analyzed and found to consist of 90.5 percent by weight of the sodium isethionate ester of oleic acid.

In a similar experiment wherein the materials were heated at temperatures between 110 and 115 C. for a cooled to room temperature.

'4 period of 5 hours the product contained only 86 percent by weight of the ester.

Example 3 A charge of 606 grams (2 moles) of stearic acid chloride and 311 grams (2.1 moles) of sodium isethionate were mixed in a laboratory blender having blades adapted to knead and mechanically work the ingredients. The mixture was kneaded and heated at temperatures between and C. for a period of 15 minutes while withdrawing by-product hydrogen chloride vapors from the reaction under vacuum and maintaining the mixture under absolute pressures of from 10 to 50 millimeters, then was heated at temperatures between and C. for a period of 30 minutes while withdrawing vapor of HCl from the reaction. The product was a granular white material. It was cooled and ground to a. powdered form. Powdered sodium hydroxide was incorporated with the product to form a substantially neutral composition. An aqueous 2 weight percent solution of the final composition in water had a pH value of 7.5. After storage of the dry composition for a period of 15 days at ordinary temperatures the pH value of an aqueous 2 percent solution of the material was unchanged.

Example 4 A charge of 545 grams (2.3 moles) of fatty acid chlorides, principally lauroyl chloride, similar to that employed in Example 1, and 358 grams (2.5 moles) of ammonium isethionate were mixed in a laboratory blender and heated at temperatures between 140 and 150 C. for a period of 30 minutes at absolute pressures between 10 and 50 millimeters while withdrawing vapors of the byproduct hydrogen chloride from the reaction, then was The product was a waxy solid. It crystallized from ethyl alcohol in the form of a fine white powder.

We claim:

1. In a process wherein a fatty acid chloride'is reacted with a salt of isethionic acid to yield a corresponding isethionate fatty acid ester, the steps which consist in mechanically working and heating in admixture with one another under substantially anhydrous conditions, a salt of isethionic acid selected from the group consisting of ammonium, alkali metal and alkaline earth metal salts of said acid, and an acid chloride of at least one fatty acid containing from 12 to 18 carbon atoms in the molecule, in proportions corresponding to from 1 to 1.1 gram molecular proportions of the salt of isethionic acid per gram molecular proportion of the fatty acid chloride, at temperatures between 135 and 170 C. and withdrawing vapors of the by-product hydrogen chloride from the reaction at substantially the rate at which it is formed to substantially complete the reaction and thereafter neutralizing the reacted material with an alkali.

2. A process as claimed in claim 1, wherein the reaction is carried out under subatmospheric pressures.

3. A process as claimed in claim 1, wherein an inert gas is fed to the reaction, thereby displacing the byproduct hydrogen chloride.

4. A process as claimed in claim 1, wherein the salt of isethionic acid is sodium isethionate.

5. A process as claimed in claim 1, wherein the salt of isethionic acid is ammonium isethionate.

6. A process as claimed in claim 1, wherein the reacted materials are neutralized with an alkali.

7. A process for making a surface active agent which comprises mechanically working and heating in admixture with one another under substantially anhydrous conditions, approximately equimolecular proportions of sodium isethionate and an acyl chloride of at least one fatty acid derived from coconut oil at temperatures between 140 and C. and subatmospheric pressure and withdrawing vapors of the by-product hydrogen chloride from the reaction at substantially the rate at which it is formed to substantially complete the reaction, then cooling the reacted material and neutralizing said material with an alkali.

8. A process as claimed in claim 7, wherein the reaction is carried out in continuous manner.

9. A process for making a surface active agent which comprises mechanically working and heating in admixture with one another under substantially anhydrous conditions, approximately equimolecular proportions of sodium isethionate and oleoyl chloride at temperatures between 140" and 160 C. and subatmospheric pressures and withdrawing vapors of the by-product hydrogen chloride from the reaction at substantially the rate at which it is formed, to substantially complete the reaction then cooling the reacted material and neutralizing said material with an alkali.

10. A process for making a surface active agent which comprises mechanically working and heating in admixture with one another under substantially anhydrous conditions, approximately equimolecular proportions of sodium isethionate and stearoyl chloride at temperatures between and C. and subatmospheric pressure and withdrawing vapors of the by-product hydrogen chloride from the reaction at substantially the rate at which it is formed to substantially complete the reaction, then cooling the reacted material and neutralizing said material with an alkali.

References Cited in the file of this patent UNITED STATES PATENTS Re. 23,823 Molteni et al., May 4, 1954 2,006,309 Clark June 25, 1935 FOREIGN PATENTS 364,107 Great Britain Dec. 28, 1931 OTHER REFERENCES Hoyt: German Chemical Developments in Synthetic Detergents and Wetting Agents, 1951, pages 20, 27, 28. 

1. IN A PROCESS WHEREIN A FATTY ACID CHLORIDE IS REACTED WITH A SALT OF ISETHIONIC ACID TO YIELD A CORRESPONDING ISETHIONATE FATTY ACID ESTER, THE STEPS WHICH CONSIST IN MECHANICALLY WORKING AND HEATING IN ADMIXTURE WITH ONE ANOTHER UNDER SUBSTANTIALLY ANHYDROUS CONDITIONS, A SALT OF ISETHIONIC ACID SELECTED FROM THE GROUP CONSISTING OF AMMONIUM, ALKALI METAL AND ALKALINE EARTH METAL SALTS OF SAID ACID, AND AN ACID CHLORIDE OF AT LEAST ONE FATTY ACID CONTAINING FROM 12 TO 18 CARBON ATOMS IN THE MOLECULE, IN PROPORTIONS CORRESPONDING TO FROM 1 TO 1.1 GRAM MOLECULAR PROPORTIONS OF THE SALT OF ISETHIONIC ACID PER GRAM MOLECULAR PROPORTION OF THE FATTY ACID CHLORIDE, AT TEMPERATURES BETWEEN 135* AND 170*C. WITHDRAWING VAPORS OF THE BY-PRODUCT HYDROGEN CHLORIDE FROM THE REACTION AT SUBSTANTIALLY THE RATE AT WHICH IT IS FORMED TO SUBSTANTIALLY COMPLETE THE REACTION AND THEREAFTER NEUTRALIZING THE REACTED MATERIAL WITH AN ALKALI. 